# git rev-parse -q --verify b75a2bf899b668b1d52de8846aafdbcf81349c73^{commit}
b75a2bf899b668b1d52de8846aafdbcf81349c73
already have revision, skipping fetch
# git checkout -q -f -B kisskb b75a2bf899b668b1d52de8846aafdbcf81349c73
# git clean -qxdf
# git log -1
commit b75a2bf899b668b1d52de8846aafdbcf81349c73
Merge: 763cfc8 346c09f
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed Apr 27 12:03:59 2016 -0700

    Merge branch 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
    
    Pull workqueue fix from Tejun Heo:
     "So, it turns out we had a silly bug in the most fundamental part of
      workqueue for a very long time.  AFAICS, this dates back to pre-git
      era and has quite likely been there from the time workqueue was first
      introduced.
    
      A work item uses its PENDING bit to synchronize multiple queuers.
      Anyone who wins the PENDING bit owns the pending state of the work
      item.  Whether a queuer wins or loses the race, one thing should be
      guaranteed - there will soon be at least one execution of the work
      item - where "after" means that the execution instance would be able
      to see all the changes that the queuer has made prior to the queueing
      attempt.
    
      Unfortunately, we were missing a smp_mb() after clearing PENDING for
      execution, so nothing guaranteed visibility of the changes that a
      queueing loser has made, which manifested as a reproducible blk-mq
      stall.
    
      Lots of kudos to Roman for debugging the problem.  The patch for
      -stable is the minimal one.  For v3.7, Peter is working on a patch to
      make the code path slightly more efficient and less fragile"
    
    * 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
      workqueue: fix ghost PENDING flag while doing MQ IO
# < /opt/cross/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-gcc --version
# < git log --format=%s --max-count=1 b75a2bf899b668b1d52de8846aafdbcf81349c73
# < make -j 48 ARCH=arm O=/home/kisskb/slave/build/linus_realview-smp_defconfig_arm CROSS_COMPILE=/opt/cross/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-  realview-smp_defconfig
make[2]: *** [realview-smp_defconfig] Error 1
make[1]: *** [realview-smp_defconfig] Error 2
make: *** [sub-make] Error 2
Command 'make -j 48 ARCH=arm O=/home/kisskb/slave/build/linus_realview-smp_defconfig_arm CROSS_COMPILE=/opt/cross/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-  realview-smp_defconfig' returned non-zero exit status 2
# rm -rf /home/kisskb/slave/build/linus_realview-smp_defconfig_arm
# Build took: 0:00:02.361031